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Russian Geology and Geophysics

2005 year, number 10

THE 25 SEPTEMBER 2002 VITIM METEORITE: RESULTS OF COMPLEX RESEARCH

V.S. Antipin, S.A. Yazev*, A.B. Perepelov, S.V. Efremov, M.A. Mitichkin, A.V. Ivanov**, L.A. Pavlova, N.S. Karmanov***, and Z.F. Ushchapovskaya**
Keywords: Bolide, meteorite, ablation track, electrophone phenomena, nickel-iron, spherules
Pages: 1037-1052

Abstract

On September 25, 2002, a brilliant meteor was observed over the Mama-Chuya and Bodaibo Districts of the Irkutsk Region. Its flight was accompanied by significant light, sound, and electrophone phenomena as well as by an air shock wave. A U.S. satellite has recorded the coordinates of two observation points, and many eye-witnesses have testified to this natural phenomenon. On the basis of this information, the path of the meteorite fall has been reconstructed. In 2002-03, three expeditions explored the area where the meteorite had supposedly fallen. The main results of their complex research are reported in this paper.
In addition to the expeditions of the Irkutsk Scientific Center, experts from the Meteorite Agency of the RAS as well as teams of research workers and students from Ekaterinburg and Krasnoyarsk were engaged in the search for the meteorite matter. Neither of these groups succeeded in finding craters, or traces of fall, or fragments of this meteorite.
Examining the snow samples taken along the path of the meteorite flight, we have found mineral particles and spherules, whose origin might be linked to the cosmogenic matter precipitated from the smoke-dust ablation track of the meteorite, and analyzed them using an electron microprobe. Of the greatest interest for study are polymineral spherules and a particle of Ni-bearing pyrites and nickel-iron, whose Fe and Ni proportions correspond to those of kamacite and taenite, typical minerals of meteorites. Analysis of these mineral formations shows that they are not typical of the bedrock and weathering crust of the study area but are, in particular, similar to the spherules (micrometeorites) from the Antarctic ice discovered in the purposeful search for meteorite matter. An important argument for the meteorite origin of the found particles is the fact that the localities where they were found during the expeditions coincide with the areas of damaged and fallen forest along the projected path of the meteor.